Well the email survey certainly has changed and spurred the conversation. Sounds like whatever theme is chosen for the GG overhaul will set the stage for our next B&M wonder to anchor that area in phase two.
Having a legitimate coaster in that area would be a monumental addition for improving park flow.
As far as Phase One is concerned, I can't say I'm enamored by the idea of adding a few more kiddie rides and a shot tower or drop tower, but... if it "replaces" GG which has been begging for some TLC for a while, and leads to a major addition following, I'm all for it.
All that said, of the thematic options presented, I would vote for the fireworks factory all day long with on caveat. I would hope it's done with a very rustic approach, versus bright, bold colors as the concept art illustrates. Despite how well GE was done in terms of detail, I think it's very out of theme and character for the period in which the bulk of SDC so magically recreates.
The idea of the fireworks factory fits in beautifully (so long as it's done right). After all, four of SDC's five coasters have already been developed and themed around the idea of fire/explosives...FITH,TNT,PK,WF.
If the new theme chosen is in fact the fireworks factory approach, they should borrow pages from our other coaster queues and stories, and really work to make it blend seamlessly with the rest of the park. I would hate to see GE's out of theme palette spill over into the GG area with updated attractions that stick out like a throbbing thumb.